Slot machine and playing method thereof

ABSTRACT

A slot machine is operable to cause, when a sub game in which a specific symbol is selected from among a plurality of symbols by an external input was executed, a predetermined number of times of special game as a unit game to be executed after the sub game, vary a payout amount of credits in accordance with the appearance frequency of the specific symbol on a main display during the special game, and display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of U.S. Provisional Application No. 60/850,272, filed on Oct. 10, 2006; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a slot machine for playing a game using game media such as coins or bills, and a playing method thereof.

2. Description of Related Art

As conventional slot machines, there is one disclosed in U.S. Pat. No. 6,960,133B1 or U.S. Pat. No. 6,012,983. The slot machine is configured such that a plurality of symbols starts to be scrolled on a display unit provided in front of a cabinet when the player inserts game media such as tokens, coins or bills into the insertion slot of the slot machine and presses the spin button, and subsequently, respective symbols automatically come to a stop. At this time, symbols to be stopped are determined randomly by generating a random number at the start of scrolling respective symbols, which is triggered by pressing the spin button. With winning a bonus game such as a mystery bonus or the second game after this determining process of the symbols to be stopped, payout of credits accompanying the award such as a mystery bonus is executed, or transition from the base game to the bonus game occurs and the bonus game is executed. Here, the slot machine is configured to payout a predetermined award when a winning combination occurs during execution of the game.

In U.S. Pat. No. 6,093,102, a slot machine is disclosed, in which an award is paid out when symbols are put on a specific line called a payline. In U.S. Pat. No. 6,604,999B2 or US2002065124A1, a slot machine is disclosed, in which two kinds of payouts are made, that is, the payout determined by a combination of symbols having come to a stop on the payline and the payout determined by the number of displayed symbols called a scatter (hereinafter, referred to as a scatter symbol) not affected by the payline.

The scatter symbol in such a slot machine serves as a trigger for payout depending on the number of symbols.

SUMMARY OF THE INVENTION

A first aspect of the present invention is a slot machine comprising a configuration described below, the slot machine comprising a main display on which a plurality of symbols that have been arranged are rearranged in a unit game, a sub display on which an appearance frequency of a specific symbol and a payout amount of credits in accordance with the appearance frequency are displayed, and a controller operable to: (a) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, cause a predetermined number of times of special game as a unit game to be executed after the sub game, (b) vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, and (c) display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.

With the slot machine according to the first aspect of the present invention, when a specific symbol is selected by the player's operation, the controller controls the payout amount of credits to vary in accordance with the appearance frequency of the specific symbol on the main display during the special game, that is, the unit game. Further, the controller controls the appearance frequency of the specific symbol and the payout amount of credits in accordance with the appearance frequency to be displayed on the sub display.

A second aspect of the present invention is a slot machine comprising a configuration described below, the slot machine comprising a main display on which a plurality of symbols that have been arranged are rearranged in a unit game, a sub display on which the appearance frequency of a specific symbol and a payout amount of credits in accordance with an appearance frequency are displayed, and a controller operable to: (a) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, cause a predetermined number of times of special game as a unit game to be executed after the sub game, (b) vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, (c) increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout, and (d) display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.

With the slot machine according to the second aspect of the present invention, the controller controls to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout and reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout. Consequently, when the player selects a symbol having a small expectation value, the probability of payout is reduced, however, the payout amount will be increased depending on the number of rearranged symbols. Further, when the player selects a symbol having a large expectation value, the payout amount is reduced, however, the probability of payout will be increased.

A third aspect of the present invention is a slot machine comprising a configuration described below, the slot machine comprising a main display on which a plurality of symbols that have been arranged are rearranged in a unit game, a sub display on which an appearance frequency of a specific symbol and a payout amount of credits in accordance with the appearance frequency are displayed, and a controller operable to: (a) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, cause a predetermined number of times of special game as a unit game to be executed after the sub game, (b) vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, (c) increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout, and (d) update the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency each time each special game is over or the specific symbol is rearranged on the main display, and display them on the sub display.

With the slot machine according to the third aspect of the present invention, the controller controls to update the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency each time each special game is over or each time the specific symbol is rearranged on the main display and display them on the sub display.

A fourth aspect of the present invention is a playing method executed in a slot machine, comprising the steps of: (a) causing a controller to rearrange a plurality of symbols that have been arranged on a main display in a unit game, (b) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, causing the controller to execute a predetermined number of times of special game as a unit game after the sub game, and to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, and (c) causing the controller to display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.

With the playing method executed in a slot machine according to the fourth aspect of the present invention, when a specific symbol is selected by the player's operation, the payout amount of credits is controlled so as to vary in accordance with the appearance frequency of the specific symbol on the main display during the special game, that is, a unit game. Further, the appearance frequency of the specific symbol and the payout amount of credits in accordance with the appearance frequency are displayed on the sub display.

A fifth aspect of the present invention is a playing method executed in a slot machine, comprising the steps of: (a) causing a controller to rearrange a plurality of symbols that have been arranged on a main display in a unit game, (b) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, causing the controller to execute a predetermined number of times of special game as a unit game after the sub game, and to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, (c) causing the controller to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and to reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout, and (d) causing the controller to display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.

With the playing method executed in a slot machine according to the fifth aspect of the present invention, control is taken so as to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout and reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout. Consequently, when the player selects a symbol having a small expectation value, the probability of payout is reduced, however, the payout amount will be increased depending on the number of rearranged symbols. Further, when the player selects a symbol having a large expectation value, the payout amount is reduced, however, the probability of payout will be increased.

A sixth aspect of the present invention is a playing method executed in a slot machine, comprising the steps of: (a) causing a controller to rearrange a plurality of symbols that have been arranged on a main display in a unit game, processing of causing, (b) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, causing the controller to execute a predetermined number of times of special game as a unit game after the sub game, and to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, (c) causing the controller to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and to reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout, and (d) causing the controller to update the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency each time each special game is over or the specific symbol is rearranged on the main display, and to display them on the sub display.

With the playing method executed in a slot machine according to the sixth aspect of the present invention, the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency are updated each time each special game is over or the specific symbol is rearranged on the main display and they are displayed on the sub display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart generally showing a playing method of a slot machine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an appearance of a slot machine according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing columns of symbols displayed on each display area and the code number of each symbol of a slot machine according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a payout table for a base game.

FIG. 5 is an explanatory diagram showing a relationship between symbols selected in a special game and their expectation values.

FIGS. 6A to 6C are explanatory diagrams showing a payout table for a special game.

FIG. 7 is an explanatory diagram showing a display example of a count value/payout amount display.

FIG. 8 is a block diagram showing a control circuit of a slot machine according to an embodiment of the present invention.

FIG. 9 is a flow chart showing part of a procedure of base game execution processing executed by a slot machine according to an embodiment of the present invention.

FIG. 10 is a flow chart showing another part of a procedure of base game execution processing executed by a slot machine according to an embodiment of the present invention.

FIG. 11 is a flow chart showing part of a procedure of special game execution processing executed by a slot machine according to an embodiment of the present invention.

FIG. 12 is a flow chart showing another part of a procedure of special game execution processing executed by a slot machine according to an embodiment of the present invention.

FIG. 13 is a flow chart showing a procedure of symbol-to-be-stopped determination processing executed by a slot machine according to an embodiment of the present invention.

FIG. 14 is a flow chart showing a procedure of symbol scrolling processing executed by a slot machine according to an embodiment of the present invention.

FIG. 15 is a flow chart showing a procedure of bonus game processing executed by a slot machine according to an embodiment of the present invention.

FIG. 16A is an explanatory diagram showing a display example when a combination including a predetermined number of or more specific symbols is rearranged, FIG. 16B is an explanatory diagram showing a display example when a winning combination of specific symbols having come to a stop on a payline, and FIG. 16C is an explanatory diagram showing a display example when the specific symbol is included in the symbols having come to a stop in the display area.

FIG. 17A is an explanatory diagram showing a display example when symbols are scrolling, FIG. 17B is an explanatory diagram showing a display example when a winning combination of specific symbols has come to a stop on the payline, FIG. 17C is an explanatory diagram showing a display example when a winning combination of specific symbols has come to a stop on the payline, and FIG. 17D is an explanatory diagram showing a display example when a combination including a predetermined number of specific symbols has come to a stop in each display area.

FIG. 18A is an explanatory diagram showing a display example when each symbol display area is put into a lit state in a symbol selecting display, FIG. 18B is an explanatory diagram showing a display example after the symbol selection by a player in the symbol selecting display, and FIG. 18C is an explanatory diagram showing a display example in the symbol selecting display when the special game is over.

DETAILED DESCRIPTION OF THE EMBODIMENT

FIG. 1 is a flow chart generally showing a playing method of a slot machine according to an embodiment of the present invention. The general operation of the slot machine and the playing method according to an embodiment of the present invention will be described below with reference to the flow chart shown in FIG. 1 and the perspective view shown in FIG. 2.

When the slot machine according an embodiment of the present invention is powered on and starts up, authentication processing is executed first (step S100). In this authentication processing, initial checking processing is executed, prior to the start of the unit game (base game, second game, etc.), in order to determine whether the program for operating the system operates normally or not, whether there is any altercation of the program or not, etc.

Next, the base game is executed (step S200). The base game is executed by a trigger when a spin button 23 is pressed by a player in a state in which a coin is inserted into a coin insertion slot 21 by the player and a desired number of credits are bet.

On the front of a cabinet 11, a lower image display panel 16 is provided. In the lower image display panel 16, a display window 15 is provided and a liquid crystal display 17 is provided thereinside. The liquid crystal display 17 comprises a display area 28 (28 a to 28 e) for displaying symbols in a 5-column×3-row matrix. In each of the display area 28, symbols are arranged. In the base game, the scrolling of symbols arranged in each of the display area 28 is started with the pressing of the spin button by the player as a trigger. Then, after a lapse of a predetermined period of time, the scrolling stops automatically and symbols come to a stop (rearrangement) in each of the display area 28. In other words, in the base game, the unit games corresponding to five columns are executed. With the slot machine according to the present embodiment, in the base game, the processing of determining symbols to be stopped in each of the display area 28 (28 a to 28 e) is executed.

Next, whether or not a sub game is executed is determined (step S300), which selects a specific symbol from among all the symbols that can be displayed in each of the display area 28 (28 a to 28 e), that is, “JACKPOT 7”, “BLUE 7”, “BELL”, CHERRY”, “STRAWBERRY”, “PLUM”, “ORANGE”, “APPLE”, “LOBSTER”, and “CRAB”.

Then, when the sub game is determined to be executed (YES in step S300), the sub game is executed (step S400).

The selection of a specific symbol in the sub game can be performed by using, for example, a symbol selecting display 14 provided below the display window 15. In each of symbol display areas 14 a to 14 j of the symbol selecting display 14, each symbol of the “JACKPOT 7”, “BLUE 7”, “BELL”, CHERRY”, “STRAWBERRY”, “PLUM”, “ORANGE”, “APPLE”, “LOBSTER”, and “CRAB” is displayed. When the player selectively touches and operates one of the symbol display areas 14 a to 14 j in which each symbol is displayed, an input signal in accordance with a touched and operated one of the symbol display areas 14 a to 14 j is output from a touch panel 69 (refer to FIG. 8) provided on the front of the lower image display panel 16. In the present embodiment, the respective symbol display areas 14 a to 14 j are lit and displayed in the respective states of being color-coded in accordance with the expectation values of the respective symbols. Consequently, it is possible for the player to determine the magnitude of the expectation value of each symbol by its color. The expectation value of a symbol will be described later.

With the slot machine according to the present embodiment, the input signal from the touch panel 69 is handled as an external input. Then, it is possible to recognize a selected specific symbol by determining one of the symbol display areas 14 a to 14 j touched and operated by the player.

Alternatively, it may also be possible to constitute each of the symbol display areas 14 a to 14 j of the symbol selecting display 14 by a press button switch. In this case, it is possible to determine one of the symbol display areas 14 a to 14 j pressed by the player by detecting the input signal from the press button switch. In this case, it follows that the input signal from the press button switch corresponds to the external input.

After the sub game is executed, the slot machine according to the present embodiment executes the special game a predetermined number of times (step S500).

In each special game, the slot machine according to the present embodiment starts scrolling of symbols in each display area 28 (28 a to 28 e), the pressing of the spin button 23 by the player as a trigger, and then, stops scrolling to cause symbols to come to a stop in each display area 28.

Then, the slot machine according to the present embodiment counts an appearance frequency of a specific symbol selected in the sub game during the special game (step S600).

Specifically, the appearance frequency of a specific symbol during the special game is counted as follows.

In other words, the slot machine according to the present embodiment counts the number of times the “PLUM” symbol selected in the sub game is rearranged in each display area 28 as the appearance frequency of the specific symbol during the special game. Further, in the slot machine according to the present embodiment, it may also be possible to count the number of times the “PLUM” symbol selected in the sub game is rearranged (the number of times of game) as the appearance frequency of the specific symbol during the special game.

For example, it is assumed that the “PLUM” symbol is selected as a specific symbol. In this case, an award is caused to occur, which is accompanied by payout of credits in accordance with the number of rearranged “PLUM” symbols as shown in FIG. 16C. However, it may also be possible to cause an award accompanied by payout to occur by a combination of other symbols. In other words, it may also be possible to cause an award accompanied by payout to occur when a combination including a predetermined number of or more “PLUM” symbols is achieved, or when a winning combination of the “PLUM” symbols is achieved. Specifically, as a combination of the “PLUM” symbols selected in the sub game, which causes an award accompanied by payout of credits to occur, examples include a combination including a predetermined number (e.g., six) of or more “PLUM” symbols as shown in FIG. 16A and a wining combination of the “PLUM” symbols having come to a stop on the payline L as shown in FIG. 16B. Such a special game may be executed simultaneously with the base game, or may be executed alone.

After a predetermined number of times of special game are over, the slot machine according to the present embodiment makes payout of credits with the payout amount in accordance with the appearance frequency of the specific symbol counted during the special game (step S700) and executes the base game after returning to step S200.

With the slot machine according to the present embodiment, it is possible to develop the player's interest in the game by causing the player to expect that the payout amount will increase in accordance with the increase in the number of rearranged specific symbols selected in the sub game or in the number of times the specific symbol is rearranged.

In the above-mentioned example, an example in which symbols are caused to stop and displayed in the 5-column×3-row display area 28 (28 a to 28 e) is explained, however, the present invention is not limited to the 5-column×3-row display area 28.

Further, in the above-mentioned example, symbols are displayed in each of the display area 28 using the liquid crystal display 17. As another example, a configuration may also be possible, in which cylinder-shaped, mechanical spinning reels on the side of which a plurality of symbols are drawn are used and after spun, the spinning reels are stopped to cause the symbols to come to a stop inside the display window 15.

Furthermore, in the above-mentioned example, symbols are displayed by scrolling the symbols vertically with respect to each of the display areas 28 (28 a to 28 e) and then, the symbols are caused to come to a stop (rearrangement) in the base game. As another example, it may also be possible to change symbols in each of the display areas 28 (28 a to 28 e) for display (rearrangement).

Next, a configuration of a slot machine 10 according to one embodiment of the present invention will be explained with reference to the perspective view shown in FIG. 2. The slot machine 10 is installed in a gaming facility.

With the slot machine 10, a coin, a bill, or electronic redeemable value information corresponding to these is used as game media for executing a unit game. However, in the present invention, the game media is not limited in particular and may include a medal, a token, an electronic money and a ticket, for example. In addition, the above-mentioned ticket may include but not limited to a bar-coded ticket described below and the like, for example.

As shown in FIG. 2, the slot machine 10 comprises the cabinet 11, a top box 12 provided on the top side of the cabinet 11, and a main door 13 provided on the front of the cabinet 11.

Inside the cabinet 11, the liquid crystal display 17 is provided for scrolling a 5-column×3-row matrix of symbols. The liquid crystal display 17 comprises the display area 28 (28 a to 28 e) for displaying the 5-column×3-row matrix of symbols. On the front of the display area 28, the display window 15 is provided, through which symbols displayed in the display area 28 are visible. When the base game is executed, the symbols are scrolled in each of the 5-column×3-row display area 28 (28 a to 28 c). It is possible for the player to view the symbols being scrolled through the display window 15.

In the present embodiment, the 5-column×3-row display area 28 (28 a to 28 c) of the liquid crystal display 17 is described as an example. As another example, it may also be possible to display symbols through the display window 15 by spinning and then stopping mechanical reels with the symbols displayed on their side. Also, the display area 28 is not limited to the 5-column×3-row matrix.

At the upper part of the main door 13 and in front of the liquid crystal display 17, the lower image display panel 16 is provided. The lower image display panel 16 has a transparent liquid crystal panel to display, during the game, various information about the game, effect images, and the like.

A number of credit display 31, a number of payout display 32, and a count value/payout amount display 71 are provided in the lower image display panel 16. The number of coins having been credited is displayed as images on the number of credit display 31. The number of coins to be paid out, if the symbol combination that has come to a stop on the payline L described below turns out to be a winning combination, and the number of coins to be paid out, if a combination including a predetermined number (e.g., six) of or more predetermined symbols has come to a stop in the display area 28, are displayed as images on the number of payout display 32. On the count value/payout amount display 71, the symbol selected in the sub game, its appearance frequency, that is, the number of rearranged symbols (or the number of times of rearrangement), and the payout amount (the number) of credits in accordance with the appearance frequency are displayed.

In the middle portion of the display window 15 provided in the lower image display panel 16, a single payline L is set. The payline L defines a combination of symbols. When a combination of symbols having come to a stop on the payline L turns out to be a winning combination, the number of coins in accordance with the winning combination and the number of inserted coins (the number of BETs) are paid out. The payline L is set virtually and not viewed actually. However, it may also be one actually drawn on the lower image display panel 16.

Here, in the present embodiment, an example is explained, in which the single payline L is set, however, three paylines horizontally crossing the top, middle, and bottom portions of the display window 15, for example, may be possible. As another example, it may also be possible to form paylines running diagonally (V-shaped, inverted V-shaped, etc.), wherein the paylines in the number corresponding to the number of inserted coins are activated. In this case, when the symbol combination having come to a stop on the activated paylines is a winning combination accompanied by payout, coins in the number according to the combination are paid out.

Further, below the display area 28 of the lower image display panel 16, the symbol selecting display 14 is provided.

The symbol selecting display 14 comprises the plurality of the symbol display areas 14 a to 14 j for individually displaying all the symbols that can be displayed in the display area 28 (28 a to 28 e) by the liquid crystal display 17, that is, the “JACKPOT 7”, “BLUE 7”, “BELL”, “CHERRY”, “STRAWBERRY”, “PLUM”, “ORANGE”, “APPLE”, “LOBSTER”, and “CRAB”.

Each of the symbol display areas 14 a to 14 j can be lit up and displayed individually by a backlight 14L (refer to FIG. 8) arranged therebehind.

Further, on the front of the lower image display panel 16, the touch panel 69 (refer to FIG. 8) is provided and it is possible for the player to input various commands by operating the touch panel 69.

Below the lower image display panel 16 are provided a control panel 20, the coin insertion slot 21 for accepting coins into the cabinet 11, and a bill validator 22.

On the control panel 20 are provided the spin button 23, a change button 24, a cashout button 25, a 1-BET button 26, and a maximum BET button 27. The spin button 23 is a button for inputting a command to start scrolling of the symbols displayed on the display area 28. The change button 24 is a button used when requesting money exchange to the crew of a gaming facility. The cashout button 25 is a button for inputting a command to pay out the credited coins onto a coin tray 18.

The 1-BET button 26 is a button for inputting a command to bet a single coin on the game among the coins that have been credited. The maximum BET button 27 is a button for inputting a command to bet on the game a maximum number (for example, 50) of coins allowed to be bet on a single game among those that have been credited.

The bill validator 22 identifies whether or not the bill is authentic and accepts legitimate bills into the cabinet 11. Here, the bill validator 22 may also be configured so as to be able to read a bar-coded ticket 39 to be described later. A berry glass 34 having characters etc. of the slot machine 10 drawn thereon is provided on the lower front of the main door 13, that is, below the control panel 20.

On the front of the top box 12 is provided an upper image display panel 33. The upper image display panel 33 comprises a liquid crystal panel to display images representing effect images, introduction of game contents, and explanation of the game rules, for example.

In addition, a speaker 29 for audio output is provided on the top box 12. Below the upper image display panel 33 are provided a ticket printer 35, a card reader 36, a data display unit 37, and a key pad 38. The ticket printer 35 prints bar codes on the ticket, which are coded data such as the number of credits, date/time, and the identification number of the slot machine 10 and outputs the ticket as the bar-coded ticket 39. The player can play games on other slot machines using the bar-coded ticket 39, or exchange the bar-coded ticket 39 with bills at the cashier etc. of the gaming facility.

The card reader 36 reads and writes data from and to a smart card. The smart card is a card carried by the player, and stores data used for identifying the player or data relating to the game history played by the player.

The data display unit 37 comprises a fluorescent display or the like, and displays data read by the card reader 36 or data entered by the player using the key pad 38, for example. Through the key pad 38, commands or data with regard to ticketing or the like are input.

FIG. 3 is an explanatory diagram of columns of symbols to be scrolled in each of the display areas 28 (28 a to 28 e) of the liquid crystal display 17. As shown in FIG. 3, columns of a total of 22 symbols composed of code numbers “00” to “21”, respectively, are scrolled in each of the display areas 28 (28 a to 28 e). The arrangement of symbols is different for each of the display areas 28 (28 a to 28 e).

The symbols to be displayed in each of the display areas 28 (28 a to 28 e) are composed by combining the “JACKPOT 7”, “BLUE 7”, “BELL”, “CHERRY”, “STRAWBERRY”, “PLUM”, “ORANGE”, “APPLE”, “LOBSTER”, and “CRAB” symbols. Then, combinations of these symbols define combinations accompanied by payout.

The combinations accompanied by payout include combinations when winning combinations come to a stop on the payline L of the display window 15 and combinations including a predetermined number (for example, six) or more of “BELL” symbols.

Then, in the slot machine 10, a payout table for determining the payout amount (payout rate) when a combination accompanied by payout is achieved is set.

FIG. 4 is a diagram showing a payout table for a base game. The payout table for a base game is selected when the base game is executed alone. When the special game is executed, a payout table for a special game, which will be described later, is selected.

As shown in FIG. 4, a bonus trigger is invoked when the “APPLE” symbols have come to a stop on the payline L in the five display areas 28 (28 a to 28 e) and the game state shifts from the base game to the bonus game.

In addition, when a combination of the “LOBSTER” and “BELL” symbols has come to a stop on the payline L, payout of 25 coins is made. When the “CHERRY” symbols have come to a stop on the payline L, payout of 20 coins is made. When the “PLUM” symbols have come to a stop on the payline L, payout of five coins is made. When the six “BELL” symbols have come to a stop in the five display areas 28 (28 a to 28 e), payout of three coins is made.

The bonus game, which is executed when a combination of the “APPLE” symbols has come to a stop on the payline L, is a more advantageous game state than the base game. In the present embodiment, the bonus game is a free game (a game that can be played a predetermined number of times without betting coins). In the present invention, the bonus game is not particularly limited as long as it provides the player with an advantageous game state. Additionally, the bonus game that is advantageous for the player is not particularly limited as long as it is more advantageous than the base game. There may be a variety of more advantageous states such as a state in which more game media can be obtained than the base game, a state in which game media can be obtained with a higher probability than the base game, a state in which a smaller amount of game media is consumed than the base game, and so on. Specifically, bonus games may include a free game, a second game, or the like.

Scrolling of the symbols displayed (arranged) in each of the display areas 28 (28 a to 28 e) starts when the 1-BET button 26 or the maximum BET button 27 is pressed and then the spin button 23 is pressed. After a lapse of a predetermined period of time since the scrolling of respective symbols started, scrolling of respective symbols stops (rearrangement) automatically. At this time, some symbols of the columns shown in FIG. 3 come to a stop in each of the display areas 28 (28 a to 28 e).

Furthermore, various winning combinations (refer to FIG. 4) are predetermined for respective symbols and a certain number of coins to be paid out according to the winning combination are added to the credits possessed by the player when symbols composing a winning combination have come to a stop on the payline L. In addition when a bonus game is triggered, that is, when a combination of the five “APPLE” symbols has come to a stop on the payline L in the present embodiment, the game state shifts from the base game state to the bonus game state.

FIG. 5 is an explanatory diagram showing the relationship between symbols selected in the special game and their expectation values. In FIG. 5, the number of arrangements shows the total number of respective symbols, that is, the number of symbols arranged in each symbol column (refer to FIG. 3). In FIG. 5, the expectation value of payout is set to “medium” for the symbols from the “BLUE 7” having 7 as the number of arrangements to the “CHERRY” having 11 as the number of arrangements. Then, the expectation value of payout is set to “small” for the symbols having the numbers of arrangements smaller than those whose expectation value is “medium” and the expectation value is set to “large” for the symbols having the numbers of arrangements larger than those whose expectation value is “medium”. The expectation value of payout indicates whether the possibility of occurrence of an award accompanied by payout of credits is strong or faint when the symbols are rearranged. Consequently, the symbols having the small number of arrangements have a small expectation value and the symbols having the large number of arrangements have a large expectation value. In FIG. 5, for simplicity of explanation, the expectation values are represented by “large”, “medium”, and “small”, however, the expectation value can be put into a numerical value for each symbol. For example, if it is assumed that the expectation value of the “APPLE” having ten as the number of arrangements is set to “100”, the expectation value of the “JACKPOT 7” having five as the number of arrangements is “50” and the expectation value of the “PLUM” having 24 as the number of arrangements is “240”.

As explained above, the symbol display areas 14 a to 14 j are lit up and displayed in the state of being color-coded in accordance with the expectation value of each symbol. At this time, the same color is assigned to the symbols having the same expectation value. For example, color-coding is performed such that, for example, the color of the symbols having the “small” expectation value is “red”, the color of the symbols having the “medium” expectation value is “yellow”, and the color of the symbols having the “large” expectation value is “blue”. This color-coding will serve as a standard when a player selects a symbol. Consequently, a player who expects a larger payout amount although the probability of payout is low is recommended to select a symbol displayed in “red”. On the other hand, a player who expects more secure payout although the payout amount is not so large is recommended to select a symbol displayed in “blue”. In this example, color-coding into three kinds of colors is explained, however, color-coding into more kinds of colors for each expectation value may be possible.

In the slot machine of the present invention, the relationship between symbols selected in the special game and their expectation values is not limited to the example in FIG. 5. For example, in a configuration in which symbols are displayed in each of the display area 28 using the liquid crystal display 17, it may also be possible to set a specific symbol having only one arrangement only when the special game is executed.

FIGS. 6A to 6C are diagrams respectively showing a payout table (payout table for a special game) set for each symbol in the special game. The payout table for a special game is selected when the special game is being executed and is not selected when the base game is being executed alone. In the payout table for a special game, the “count value” is a value obtained by accumulating the number of rearranged symbols selected by the player (the number of symbols) in each of the display areas 28 (28 a to 28 e). For example, if it is assumed that three symbols selected in the sub game are rearranged in the first special game, the number of symbols is “three”. If it is assumed that two symbols are rearranged in the second special game, the number of symbols is “two”. Consequently, the count value at this time is “five”.

In the explanation of the present invention, the payout table (FIG. 6A) of the “JACKPOT 7” having the “small” expectation value, the payout table (FIG. 6B) of the “APPLE” having the “medium” expectation value, and the payout table (FIG. 6C) of the “PLUM” having the “large” expectation value are given as an example. For the symbols not shown in FIG. 6, the payout table is also set for each. As shown in FIGS. 6A to 6C, with the “JACKPOT 7” having the “small” expectation value, the possibility of occurrence of an award accompanied by payout of credit is faint, and therefore, the payout amount is set so as to be larger than those of the “APPLE” having the “medium” expectation value and the “PLUM” having the “large” expectation value. On the other hand, with the “PLUM” having the “large” expectation value, the possibility of occurrence of payout accompanied by payout of credits is strong, and therefore, the payout amount is set so as to be smaller than those of the “APPLE” having the “medium” expectation value and the “JACKPOT 7” having the “small” expectation value.

Consequently, it is possible for the player to expect a larger payout amount although the probability is faint when selecting a symbol having a small expectation value. On the other hand, it is possible for the player to expect more secure payout because of high probability of payout although the payout amount is not so strong when selecting a symbol having a large expectation value. In the slot machine of the present invention, the configuration of the payout table set for each symbol is not limited to the examples in FIGS. 6A to 6C.

FIG. 7 is an explanatory diagram showing a display example of the count value/payout amount display 71. Here, a case where the “JACKPOT 7” is selected by the player in the sub game is taken as an example. As shown in FIG. 7, in the count value/payout amount display 71, the “symbol name” selected in the sub game, the “count value” at that point of time, and the “payout amount” in accordance with the count value are displayed. However, as the displayed contents in the count value/payout amount display 71, only the “count value” and the “payout amount” are required at least.

Payout of credits due to the special game is made when all the special games are over. It follows that, for example, when the special game is executed ten times successively, payout of credits is made in accordance with the count value when the tenth special game is over. Consequently, it is possible for the player to confirm the final count value and payout amount when the special game is over as well as recognizing the current count value and payout amount at all times. Further, it may also be possible to make payout of credits due to the special game when the special game is over each time.

For example, when the “JACKPOT 7” is selected by the player in the sub game, the payout table for a special game shown in FIG. 6A is selected. Then, if it is assumed that three symbols selected in the sub game are rearranged in the first special game and two symbols are rearranged in the second special game, the count value will be “five” at that point of time. At this time, in the count value/payout amount display 71, the count value “five” and the payout amount of credits “twenty” are displayed when the second special game is over. Among these display contents, the “count value” and the “payout amount” are updated each time the single special game is over. In this manner, since the contents are updated each time the single special game is over, it is possible for the player to correctly grasp the current “count value” and “payout amount”. Due to this, it can be expected that the player will seek a larger payout amount and it is possible to cause the player to have an eagerness for the game continuously.

Further, it may also be possible to design the display of the “count value” and the “payout amount” by the count value/payout amount display 71 so as to be produced each time the symbol selected by the player is rearranged. In this case, it follows that if the symbol selected by the player is not rearranged, the “count value” or the “payout amount” is not displayed in each special game. Consequently, it is possible for the player to recognize whether or not the selected symbol is rearranged, that is, whether or not payout due to the selected symbol is caused to occur. Further, when at least one selected symbol is rearranged, the display is produced by the count value/payout amount display 71, and therefore, it can be expected that the player will have a concern about what numerical value is displayed and it is possible to cause the player to have an eagerness for the game continuously.

FIG. 8 is a block diagram showing a control circuit of the slot machine 10 shown in FIG. 2. As shown in FIG. 8, the control circuit comprises a motherboard 40, a main body PCB (Printed Circuit Board) 60, a gaming board 50, a sub CPU 61, a door PCB 80, and various types of components such as switches or sensors. Then, the motherboard 40 and the gaming board 50 constitute a controller 48.

The gaming board 50 comprises a CPU (Central Processing Unit) 51, a ROM 55 and a boot ROM 52, which are connected to one another by an internal bus, a card slot 53S corresponding to a memory card 53, and an IC socket 54S corresponding to a GAL (Generic Array Logic) 54.

The Memory card 53 stores game programs and game system programs. The game programs include a symbol-to-be-stopped determination program. The symbol-to-be-stopped determination program is a program for determining the symbol (code number corresponding to the symbol) to be stopped on the payline L of each of the display areas 28 (28 a to 28 e). The symbol-to-be-stopped determination program includes symbol weighting data corresponding to each of a plurality of kinds of payout rates (e.g., 80%, 84%, and 88%). The symbol weighting data indicates the relationship between the code numbers (refer to FIG. 3) of respective symbols and one or more random number values within a predetermined numerical range (0 to 256), respectively for each of the 5-column display areas 28 (28 a to 28 e).

The payout rate is defined based on the payout rate setting data that is output from the GAL 54 and based on the symbol weighting data corresponding to the payout rate, the symbols to be stopped are determined.

In addition, the card slot 53S, configured so that the memory card 53 is capable of being inserted therein and removed therefrom, is connected to the motherboard 40 by the IDE bus. Thus, the type or contents of the game to be executed on the slot machine 10 can be changed by removing the memory card 53 from the card slot 53S, writing another game program and game system program in the memory card 53, and inserting the memory card 53 into the card slot 53S.

The game programs include a program relating to the progress of the game and a program for shifting the state to the bonus game. In addition, the game programs include image data and sound data to be output during the game.

The GAL 54 comprises a plurality of input ports and output ports and, when data is entered in an input port, outputs data corresponding to the entered data from an output port. The data output from the output port is the payout rate setting data described above.

In addition, the IC socket 54S, configured so that the GAL 54 is capable of attaching thereto and removing therefrom, is connected to the motherboard 40 by the PCI bus. Consequently, the payout rate setting data to be output from the GAL 54 can be changed by removing the GAL 54 from the IC socket 54S, rewriting the program to be stored in the GAL 54, and attaching the GAL 54 to the IC socket 54S.

The CPU 51, the ROM 55, and the boot ROM 52 connected to one another by an internal bus are connected to the motherboard 40 by the PCI bus. The PCI bus transmits signals between the motherboard 40 and the gaming board 50, as well as supplying power from the motherboard 40 to the gaming board 50. The ROM 55 stores country identification information and an authentication program. The boot ROM 52 stores a preliminary authentication program and a program (boot code) by which the CPU 51 starts the preliminary authentication program.

The authentication program is a program for authenticating the game program and the game system program (alteration check program). The authentication program is a program for checking and proving that the game program and the game system program have not been altered. In other words, the authentication program is written in accordance with the procedure of authenticating the game program and the game system program. The preliminary authentication program is a program for authenticating the authentication program described above. The preliminary authentication program is written in accordance with the procedure of proving that the authentication program on which the authentication processing is performed has not been altered, that is, the procedure of authenticating the authentication program.

The motherboard 40 comprises a main CPU 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, and a communication interface 44.

The main CPU 41 comprises a function of controlling the whole of the slot machine 10. In particular, the main CPU 41 controls, when credits have been bet and the spin button 23 is pressed by the player, outputting a command signal to cause the sub CPU 61 to scroll the symbols arranged in each of the display areas 28 (28 a to 28 c) of the liquid crystal display 17, determining the symbols to be stopped at a position on the middle portion (on the payline L) after the symbols in each of the display areas 28 (28 a to 28 c) have been started scrolling, and displaying the symbols in such a manner that the determined symbols come to a stop on the payline L. The function of the controller 48 including the above-mentioned main CPU 41 is explained below.

After scrolling a plurality of symbols arranged on the main display (the liquid crystal display 17), the controller 48 controls the execution of the base game in which rearrangement is performed as a new symbol matrix. Because of this, the controller 48 determines symbols to be arranged into the symbol matrix by selecting from among the plurality of kinds of symbols and executes the rearrangement control so that the determined symbols come to a stop from the scrolling state.

In addition, the controller 48 executes control to cause payout to occur when the base game is executed and a combination for which payout will be made is rearranged in each of the display areas 28 (28 a to 28 e) of the liquid crystal display 17.

Further, the controller 48 controls the execution of the sub game in which a specific symbol accompanied by payout of credits is selected by an external input. In other words, the controller 48 controls the backlights 14L that can be turned on and off independently for each part corresponding to each of the symbol display areas 14 a to 14 j to light up once at the time of start of the special game in order to make the player select a specific symbol by the contact operation of each of the symbol display areas 14 a to 14 j of the symbol selecting display 14.

In addition, the controller 48 controls all the parts, except for the part corresponding to, for example, the symbol display area 14 f of the “PLUM” of the backlight 14L contacted and operated by the player and kept lit up, corresponding to other symbol display areas 14 a to 14 e and 14 g to 14 j of the backlights 14L in order to display the specific symbol selected by the player. When one symbol is selected by the contact operation of the player, the code number (refer to FIG. 3) of the symbol is stored in the RAM 43.

In addition, after a specific symbol is selected by the execution of the sub game, the controller 48 scrolls a plurality of symbols to be arranged on the main display (the liquid crystal display 17) and controls the execution of the special game in which rearrangement is performed as a new symbol matrix. Because of this, the controller 48 determines symbols to be arranged into the symbol matrix by selecting from among the plurality of kinds of symbols and executes the rearrangement control to cause the determined symbols to come to a stop from the scrolling state.

In addition, the controller 48 executes control to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol selected by the player on the main display (the liquid crystal display 17) during the predetermined number of times of the special game. In other words, the controller 48 controls to increase the payout amount of credits in accordance with the increase in the umber of specific symbols rearranged on the main display. Alternatively, the controller 48 controls to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the predetermined number of times of the special game.

In addition, the controller 48 executes control to display the specific symbol selected by the player, the number of specific symbols rearranged on the main display (or the number of times of rearrangement), and the payout amount of credits in accordance with the number of rearranged symbols (or the number of times of rearrangement) on the count value/payout amount display 71. Further, the controller 48 controls to update and display the display contents each time each special game is over or each time the specific symbol is rearranged on the main display.

In addition, during the predetermined number of times of special game, the controller 48 controls to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of a symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout and also controls to reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of a symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout.

The ROM 42 stores programs such as a BIOS (Basic Input/Output System) executed by the main CPU 41 and also stores data to be used permanently. When the BIOS is executed by the main CPU 41, initialization processing of each peripheral unit is executed and read processing of reading the game program and the game system program stored in the memory card 53 via the gaming board 50 is started. The ROM 42 also stores data of the payout table for a base game shown in FIG. 4 and data of the payout table for a special game shown in FIGS. 6A to 6C. The data is read in accordance with the symbol selected by the player in the game being executed or in the sub game.

The RAM 43 stores data and programs used when the main CPU 41 executes the processing.

The communication interface 44 establishes communication with the host computer and the like provided in the gaming facility via a communication network.

In addition, the main body PCB (Printed Circuit Board) 60 and the door PCB 80, which will be described below, are connected to the motherboard 40 by a USB (Universal Serial Bus), respectively. Further, a power supply unit 45 is connected to the motherboard 40. When electric power is supplied to the motherboard 40 from the power supply unit 45, the main CPU 41 of the motherboard 40 is activated, and electric power is also supplied to the gaming board 50 via a PCI bus, activating the CPU 51.

Devices and units that generate input signals to be fed to the main CPU 41, as well as devices and units whose operation is controlled by control signals output from the main CPU 41 are connected to the main body PCB 60 and the door PCB 80. The main CPU 41 executes arithmetic processing and stores the result in the RAM 43, or transmits control signals to respective devices and units as control processing for the respective devices and units, by executing the game program and the game system program stored in the RAM 43, based on input signals fed to the main CPU 41.

To the main body PCB 60 are connected: the sub CPU 61, a hopper 66, a coin detecting unit 67, a graphic board 68, the speaker 29, the touch panel 69, the bill validator 22, the ticket printer 35, the card reader 36, a key switch 38S, the data display unit 37, and the backlight 14L.

The sub CPU 61 controls the scrolling of the symbols in the 5-column display area 28 (28 a to 28 e) provided on the liquid crystal display 17, and is connected to a VDP (Video Display Processor) 46.

The VDP 46 reads out the image data of symbols stored in an image data ROM 47, generates scroll images to be displayed on the liquid crystal display 17, and outputs the scroll images to the liquid crystal display 17.

The hopper 66 is provided inside the cabinet 11 and pays out a predetermined number of coins from a coin payout opening 19 to the coin tray 18 based on control signals output from the main CPU 41. The coin detecting unit 67 is provided inside the coin payout opening 19 and outputs the input signal to the main CPU 41 when it has detected that a predetermined number of coins have been paid out from the coin payout opening 19.

The graphic board 68 controls the image display in the upper image display panel 33 and the lower image display panel 16 based on the control signal output from the main CPU 41. In other words, the graphic board 68 controls display of symbols to be displayed in each of the display areas 28 (28 a to 28 e), the color-coded display of each symbol in each of the symbol display areas 14 a to 14 j of the symbol selecting display 14, and the display of other images except for the turning on and off of each part corresponding to each of the symbol display areas 14 a to 14 j of the backlight 14L in the lower image display panel 16.

The number of credits stored in the RAM 43 is displayed on the number of credit display 31 (not shown in FIG. 8) of the lower image display panel 16 and the number of coins to be paid out is displayed on the number of payout display 32 (not shown in FIG. 8) of the lower image display panel 16. Further, the symbol selected in the sub game, the number of rearranged symbols in question (or the number of times of rearrangement), and the payout amount of credits in accordance with this are displayed on the count value/payout amount display 71 (not shown in FIG. 8). In addition, the graphic board 68 comprises a VDP for generating image data based on control signals output from the main CPU 41, a video RAM for temporarily storing the image data generated by the VDP, etc.

The bill validator 22 reads the images of the bills to accept legitimate bills into the cabinet 11. In addition, upon accepting a legitimate bill, the bill validator 22 outputs an input signal to the main CPU 41 according to the value of the bill. The main CPU 41 stores, in the RAM 43, a number of credits corresponding to the value of the bill, the value having been transmitted by the input signal.

The ticket printer 35 prints, based on the control signal output from the main CPU 41, bar codes on the ticket expressing coded data such as number of credits stored in the RAM 43, time and date, identification number of the slot machine 10, or the like, and outputs the ticket as the bar-coded ticket 39.

The card reader 36 reads data from the smart card and transmits the data to the main CPU 41, or writes data into the smart card based on the control signal from the main CPU 41. The key switch 38S is provided on the key pad 38 and outputs, when the key pad 38 is operated by the player, the input signal to the main CPU 41.

On the data display unit 37, the data read by the card reader 36 or the data entered via the key pad 38 by the player is displayed based on the control signal output from the main CPU 41.

The control panel 20, a reverter 21S, a coin counter 21C, and a cold cathode tube 81 are connected to the door PCB 80. On the control panel 20, a spin switch 23S corresponding to the spin button 23, a change switch 24S corresponding to the change button 24, a cashout switch 25S corresponding to the cashout button 25, a 1-BET switch 26S corresponding to the 1-BET button 26, and a maximum BET switch 27S corresponding to the maximum BET button 27 are provided. The respective switches 23S to 27S output, when their corresponding buttons 23 to 27 are operated by the player, the input signal to the main CPU 41.

The coin counter 21C is provided inside the coin insertion slot 21 and discriminates whether or not the coin inserted into the coin insertion slot 21 by the player is legitimate. Coins other than legitimate ones are ejected from the coin payout opening 19. In addition, upon detecting a legitimate coin, the coin counter 21C outputs the input signal to the main CPU 41.

The reverter 21S operates based on the control signal output from the main CPU 41 to sort the coins recognized as legitimate coins by the coin counter 21C to either the cashbox (not shown) or the hopper 66 provided inside the slot machine 10. In other words, when the hopper 66 is filled with coins, legitimate coins are sorted to the cashbox by the reverter 21S. On the other hand, when the hopper 66 is not filled with coins, legitimate coins will be sorted to the hopper 66.

The cold cathode tube 81 functions as a backlight provided in the lower image display panel 16 and on the backside of the upper image display panel 33, and lights up based on the control signal output from the main CPU 41.

Next, the specific processing performed in the slot machine 10 is explained. After performing authentication processing shown in FIG. 1, the slot machine 10 sequentially reads the game program and the game system program and executes the following base game. Prior to the execution of the base game, the controller 48 performs the initial setting. In the initial setting, the controller 48 resets to zero the counter that indicates the number of stopped specific symbols selected by the player during the special game, that is, the count value M of the counter that indicates the number of stopped symbols in the RAM 43. Further, the controller 48 also resets to zero the count value N of the counter that indicates the number of times of execution in the RAM 43, indicating the number of times of execution of the special game.

FIG. 9 and FIG. 10 are flow charts showing the specific processing procedure of the base game execution processing shown in step S200 in FIG. 1.

In the base game execution processing, first, the controller 48 determines whether or not coins are bet (step S11). In this processing, the controller 48 determines whether or not the input signal output from the 1-BET switch 26S when the 1-BET button 26 is pressed by the player, or the input signal output from the maximum BET switch 27S when the maximum BET button 27 is pressed by the player is received. When it is determined that coins are not bet by the player, the processing is returned to step S11.

On the other hand, in step S11, when it is determined that coins are bet by the player, the controller 48 performs processing of reducing the number of credits stored in the RAM 43 in accordance with the number of bet coins (step S12). If the number of coins to be bet is greater than the number of credits stored in the RAM 43, the processing of reducing the number of credits stored in the RAM 43 is not performed and the processing is returned to step S11. Further, if the number of coins to be bet exceeds the upper limit value (50, in the present embodiment) that can be bet on the single game, the processing of reducing the number of credits stored in the RAM 43 is not performed and the processing is advanced to step S13. In this state, the symbols can be scrolled in the display areas 28 (28 a to 28 e).

Next, the controller 48 determines whether or not the spin button 23 is turned ON by the player (step S13). In this processing, the controller 48 determines whether or not the input signal output from the spin switch 23S when the spin button 23 is turned ON is received.

If it is determined that the spin button 23 is not turned ON by the player, the processing is returned to step S11. When the spin button 23 is not turned ON by the player (for example, a command to end the game is input without the spin button 23 being not turned ON by the player), the controller 48 cancels the result of reduction in step S12.

In the present embodiment, the case is explained where the processing of reducing the number of credits (step S12) is performed after coins are bet by the player (step S11) and before determination is made as to whether or not the spin button 23 is turned ON (step S13). However, the present invention is not limited to this example. For example, it may also be possible to determine whether or not the spin button 23 is turned ON by the player (step S13) after coins are bet by the player (step S11) and then perform the processing of reducing the number of credits (step S12) when it is determined that the spin button 23 is turned ON by the player (YES in step S13).

Then, in step S13 in FIG. 9, when it is determined that the spin button 23 is turned ON by the player, the controller 48 performs the symbol-to-be-stopped determination processing (step S14). In this symbol-to-be-stopped determination processing, the controller 48 determines the symbols to be displayed through the display window 15 when the symbols come to a stop in each of the display areas 28 (28 a to 28 e) by executing the symbol-to-be-stopped determination program stored in the RAM 43. Due to this, the combination of symbols that come to a stop on the payline L is determined.

Next, the controller 48 performs the scroll processing of symbols (step S15). This processing is processing of causing symbols to come to a stop in each of display areas 28 (28 a to 28 e) so that the symbols determined in step S14 come to a stop on the payline L after starting the scrolling of the symbols as shown in FIG. 17A, for example, in each of the display areas 28 (28 a to 28 e).

Next, the controller 48 determines whether or not the bonus trigger has been established, for example, whether or not the combination of the “APPLE” symbols as shown in FIG. 17, for example, has stopped on the payline L (step S16). Then, when it is determined that the bonus trigger has been established, the bonus game processing to be described later is executed (step S17).

When the bonus trigger has not been established, the controller 48 determines whether or not the combination of symbols having come to a stop in each of display area 28 is a combination for which payout will be made as shown in the flow chart in FIG. 10 (step S18).

By the way, that the combination of symbols having come to a stop in each of the display area 28 is a combination for which payout will be made can be recognized by the event of the combination including only the “BELL” symbols or the “PLUM” symbols having come to a stop on the payline L, as shown in FIG. 17C or FIG. 16B, for example, or the combination including a predetermined number (six, in FIG. 17D) of “BELL” symbols having come to a stop in each of the display area 28, as show in FIG. 17D.

Then, when the combination of symbols having come to a stop in each of the display area 28 is a combination for which payout will be made (YES in step S18), the payout processing is executed for the combination of symbols having come to a stop in each of the display area 28 by applying the payout amount defined in the payout table for a base game in FIG. 4 (step S19).

After this, the controller 48 determines whether or not the start condition of the special game has been established (step S20).

The start condition of the special game can be determined to be established when the random number value defined by a random number signal, which is generated in accordance with the timing at which the spin button 23 is turned ON by the player by executing the random number generation program included in the base game execution program, coincides with the random number programmed in advance to be winning.

Here, when the start condition of the special game has not been established (NO in step S20), the controller 48 ends the one-time base game execution processing and shifts the processing to the next base game execution processing. On the other hand, when the start condition of the special game has been established (YES in step S20), the controller 48 executes the special game execution processing (step S21).

FIG. 11 and FIG. 12 are the flow charts showing the specific processing procedure of the special game execution processing shown in step S21 in FIG. 10.

In the special game execution processing, first, the controller 48 executes the symbol selection processing (step S31). This symbol selection processing corresponds to the sub game explained in step S400 in FIG. 1. Then, in the symbol selection processing, the controller 48 first lights up all the parts of the backlight 14L to bring each of the symbol display areas 14 a to 14 j of the symbol selecting display 14 into the lit state. At this time, each symbol is lit and displayed in the state of being color-coded in accordance with its expectation value. In FIG. 18A, an example is shown in which symbols are color-coded in, for example, “red”, “yellow”, and “blue” in accordance with the expectation values “large”, “medium”, and “small” shown in FIG. 5. By lighting and displaying symbols in the state of being thus color-coded, it is made possible for the player to easily identify the expectation value of each symbol.

Next, when the contact operation of the touch panel 69 is performed by the player, the contact position is detected and the symbol selected by the player is recognized.

Subsequently, the controller 48 turns off all the parts of the backlight 14L excluding the part corresponding to the symbol selected by the player, as shown in FIG. 18B. Then, only the symbol display area 14 a (14 b to 14 j) corresponding to the symbol selected by the player is brought into the lit state. In the following explanation of the present embodiment, it is assumed that the player selects the “PLUM” symbol.

The processing in step S32 to step S36 to be performed subsequently is the same as the base game execution processing in step S11 to S15 and therefore the explanation is omitted.

In step S36, after starting the scrolling of symbols and executing the processing of causing symbols to come to a stop in each of the display areas 28 (28 a to 28 e), the controller 48 determines whether or not the “PLUM” symbol selected by the player by the contact operation of the touch panel 69 is included in the symbols having come to a stop in each of the display area 28 (step S37).

Then, as shown in FIG. 16C, when the symbol “PLUM” selected by the player is included in the symbols having come to a stop in each of the display area 28 (YES in step S37), the number of “PLUM” symbols (three, in the case of FIG. 16C) selected by the player is added (accumulated) to the count value M of the counter that indicates the number of stopped symbols (step S38).

Subsequently, the controller 48 refers to the payout table for a special game (refer to FIG. 6C) corresponding to the “PLUM” symbol selected by the player, acquires the current count value and the payout amount corresponding to the count value, and displays them on the count value/payout amount display 71 by associating with the symbol selected by the player (step S39). The count value/payout amount display processing in the present embodiment is performed each time the one-time special game is over. Consequently, the contents displayed in the count value/payout amount display 71 are updated each time the one-time special game is over.

Next, after incrementing the count value N of the execution number counter in the RAM 43, which indicates the number of times of execution of the special game, by “one” (step S40), the controller 48 determines whether or not the count value N of the execution number counter has reached a predetermined value (ten in the present embodiment), that is, whether or not the special game has been executed a predetermined number of times (ten, in the present embodiment) (step S41).

When the count value N of the execution number counter has reached ten (YES in step S41), the controller 48, regarding that the number of times of execution of the special game has reached ten, determines whether or not payout for the specific symbol selected by the player has occurred during the ten special games (step S42). Here, if the payout has occurred, the payout processing in accordance with the count value M of the counter that indicates the number of stopped symbols in the RAM 43 is executed by applying the payout table for a special game (refer to FIG. 6C) corresponding to the “PLUM” symbol selected by the player (step S43).

Then, the controller 48 resets to zero the count value M of the counter that indicates the number of stopped symbols and the count value N of the execution number counter in the RAM 43. In addition, as shown in FIG. 18C, the controller 48 turns off all the parts of the backlight 14L to bring each of the symbol display areas 14 a to 14 j of the symbol selecting display 14 into the unlit state (step S44), ends the special game, and shifts the processing to the base game execution processing again.

When coins to be paid out are saved, the controller 48 adds a predetermined number of credits to the number of credits stored in the RAM 43. When coins are paid out, the controller 48 makes payout of a predetermined number of coins by transmitting the control signal to the hopper 66. At this time, the coin detecting unit 67 counts the number of coins to be paid out from the hopper 66 and when the counted number reaches a specified number, transmits the payout completion signal to the controller 48. Due to this, the controller 48 terminates the drive of the hopper 66 and completes the coin payout processing.

Consequently, in the slot machine 10 in the present embodiment, after the start condition of the special game is established and the specific symbol (for example, “PLUM”) is selected by the player, and while the special game is being executed ten times, the payout amount of credits due to the symbol will increase in accordance with the increase in the number of specific symbols rearranged in the display area 28.

Next, the symbol-to-be-stopped determination processing shown in step S14 in FIG. 9 is explained with reference to the flow chart shown in FIG. 13.

FIG. 13 is the flow chart showing the procedure of the symbol-to-be-stopped determination processing shown in step S14 in FIG. 9. This processing is one performed by the execution of the symbol-to-be-stopped determination program stored in the RAM 43 by the controller 48.

First, the controller 48 executes the random number generation program included in the symbol-to-be-stopped determination program. Then, the controller 48 selects a random number value corresponding to the display area 28 (28 a to 28 e) in each column from among the numerical value range of 0 to 255 (step S51).

Next, the controller 48 refers to the symbol weighting data in accordance with the payout rate setting data output from the GAL 54 and stored in the RAM 43. Then, based on the five selected random number values, the controller 48 determines the code number (refer to FIG. 3) of each of the display areas 28 (28 a to 28 e) (step S52).

The code number in each of the display areas 28 (28 a to 28 e) corresponds to the code number of the symbol having come to a stop and being displayed on the payline L. The controller 48 determines a winning combination by determining the code number of each of the display areas 28 (28 a to 28 e). For example, if the code number in each of the display areas 28 (28 a to 28 e) is determined as “00”, “00”, “00”, “00”, and “00”, respectively, it follows that the controller 48 has determined the “JACKPOT 7” as a winning combination.

FIG. 14 is a flow chart showing the scroll processing of the symbols shown in step S15 in FIG. 9. Incidentally, this processing is one performed between the controller 48 and the sub CPU 61.

First, the controller 48 transmits the start signal to the sub CPU 61 to the effect that the symbols are started to be scrolled in the display area 28 of the liquid crystal display 17 (step S61). Upon receipt of the start signal from the controller 48, the sub CPU 61 outputs a command to scroll the symbols to the VDP 46. The VDP 46 reads the image data of the symbols stored in the image data ROM 47 and scrolls the symbols in the 5-column display area 28 (28 a to 28 e) of the liquid crystal display 17 (step S71). Due to this, the symbols are started to be scrolled in each of the 5-column display area 28 (28 a to 28 e).

After transmitting the start signal to the sub CPU 61 in step S61 shown in FIG. 14, the controller 48 performs the effect when scrolling the symbols (step S62). This processing is processing of displaying the image on the lower image display panel 16 or outputting sounds from the speaker 29, etc., over the period of time (for example, three seconds) determined in accordance with the result etc. of the symbol-to-be-stopped determination processing (step S14 in FIG. 9).

Next, the controller 48 determines whether or not it is proper timing to direct the scrolling to stop (step S63 in FIG. 13).

In the processing in step S63, when it is determined that it is not proper timing to direct the scrolling to stop, the processing is returned to step S63 and the effect when scrolling is performed continuously. If it is determined that it is proper timing to direct the scrolling to stop in the processing in step S63, the controller 48 transmits the code number of the symbol stored in the RAM 43 to the sub CPU 61 (step S64). Upon receipt of the code number of the symbol from the controller 48, the sub CPU 61 determines a position to stop the scrolling so as to correspond to the code number (step S72).

After this, the processing of stopping the scrolling is performed and the symbols come to a stop and are displayed in each of the display areas 28 (28 a to 28 e) (step S73). In addition, the display processing of the effect image by the controller 48 is terminated (step S65).

FIG. 15 is the flow chart showing the bonus game processing shown in step S17 in FIG. 9. In the bonus game processing, first, the controller 48 determines the number of bonus games to be executed T from among 10 to 25 games based on the random number value obtained by executing the random number generation program included in the symbol-to-be-stopped determination program stored in the RAM 43 (step S81). The controller 48 stores the data of the determined number of bonus games to be executed T in the RAM 43.

Next, the controller 48 performs the symbol-to-be-stopped determination processing (step S82) and the symbol scroll processing (step S83). The processing in step S82 is substantially the same processing as that explained using FIG. 13. Further, the processing in step S83 is substantially the same processing as that explained using FIG. 14. These processing is already explained and therefore their explanation is omitted.

Next, in FIG. 15, the controller 48 determines whether or not the bonus game trigger has been established, that is, whether or not the combination of the “APPLE” has come to a stop on the payline L formed in the display area 28 (28 a to 28 e) (step S84). When it is determined that the bonus game trigger has been established (YES in step S84), the number of repetition times of the bonus game t is newly determined (step S85). Then, the determined number of repetition times t is added to the current number of times of bonus game T (step S86). Due to this, if the bonus game is won again during the bonus game, the remaining number of times of bonus game increases.

If the bonus game trigger has not been established, the controller 48 determines whether or not a combination for which payout will be made has come to a stop in each of the display area 28 (step S87).

It is possible to determine that a combination for which payout will be made has come to a stop in each of the display area 28 by the event in which the winning combination of the “BELL”, “CHERRY”, or “PLUM” has been achieved on the payline L or a combination including a predetermined number (for example, six) or more of “BELL” symbols has come to a stop in each of the display area 28, which combinations are defined in the payout table for a base game in FIG. 4.

When it is determined that a combination for which payout will be made has come to a stop in each of the display area 28 (YES in step S87), the controller 48 makes payout of coins in accordance with the number of inserted coins and the winning combination (step S88). At this time, the payout based on the payout table for a base game shown in FIG. 4 is made.

When the processing in step S86 or S88 is executed, or it is determined in step S87 that a combination for which payout will be made has not come to a stop in each of the display area 28 (when it is determined to be losing), the controller 48 reads the number of times of bonus game T stored in the RAM 43 and subtracts “one” from the value of the read number of times of game T. Then, the controller 48 stores again the number of times of game T after subtraction in the RAM 43 (step S89).

Next, the controller 48 determines whether or not the number of times of bonus game T has reached the number of times determined in step S81 (step S90). Specifically, determination is made depending on whether or not the stored number of times of game T has reached zero, and when the number of times of game T is not zero, that is, when it is determined that the number of times of execution of the bonus game has not reached the number of times determined in step S81, the processing is returned to step S82 and the above-described processing is repeated.

On the other hand, when the number of times of game T is zero, that is, it is determined that the number of times of execution of the bonus game has reached the number of times of game T determined in step S81, the processing is terminated. In this manner, the bonus game is performed.

As described above, with the slot machine 10 according to the present embodiment, the more the number of rearranged specific symbols selected by the player increases during the ten times of special game, the more the payout amount of credits due to the specific symbol increases. Consequently, it is possible to further develop the player's interest in the game by causing the player to expect to receive more payout of credits depending on the number of rearranged symbols selected by the player.

Further, in the slot machine 10 according to the present embodiment, when the specific symbol selected by the player is a symbol having a small expectation value of payout, control is taken so that the payout amount of credits in accordance with the number of rearranged symbols is made larger than that of the symbol having a large expectation value of payout and when the specific symbol selected by the player is a symbol having a large expectation value of payout, control is taken so that the payout amount of credits in accordance with the number of rearranged symbols is made smaller than that of the symbol having a small expectation value of payout. According to this, it follows that when the player selects a symbol having a small expectation value, the probability of payout is reduced, however, the player will receive a more payout amount of credits depending on the number of rearranged symbols. In this manner, since it is possible to cause a player who prefers a game taking on much of a gambling nature to expect to receive a more payout amount of credits, the interest of the player in the game can be developed. On the other hand, when the player selects a symbol having a large expectation value, it follows that the player will receive payout of credits more securely because the probability of payout is increased. In this manner, since it is possible to cause a player who does not prefer a game taking on much of a gambling nature to expect more secure payout, the interest of the player in the game can be developed.

Further, in the slot machine 10 according to the present embodiment, the display contents in the count value/payout amount display 71 are updated each time the one-time special game is over, and therefore, it is possible for the player to accurately grasp the current “count value” and “payout amount”. Due to this, it can be expected that the player will seek more payout and it is possible to cause the player to have an eagerness for the game continuously.

In the case of the configuration in which the display contents in the count value/payout amount display 71 are updated each time the symbol selected by the player is rearranged, it is possible for the player to recognize whether or not the symbol selected by the player is rearranged, that is, whether or not the payout due to the selected symbol is caused to occur from the presence/absence of the display. In other words, when at least one selected symbol is rearranged, display is produced and therefore it can be expected that the player has interest in what numerical value is displayed and it is possible to cause the player to have an eagerness for the game continuously.

In the present embodiment, the case where the specified number of times of special game is ten is explained. In this case, each time the special game is executed ten times, the symbols selected by the player, the count value up to that time, etc., are reset automatically. Consequently, if the player aborts ten times of special game halfway, it follows that the next player continues the remaining times of special game with the symbol selected by the former player and the count value. Here, if the former player has selected a symbol in expectation of more payout and the next player expects more secure payout, it follows that the next player is obliged to continue the remaining times of game under the condition that does not match the player's desire. Further, even if the player remains the same, there can be a case where the player feels to select a symbol having a different expectation value during the special game. In this case also, it follows that the player is obliged to continue the remaining times of game under the condition that does not match the player's desire. Then, it may also be possible to provide a reset button on the control panel 20 in the configuration so that when the reset button is pressed, the count value M of the counter that indicates the number of stopped symbols and the count value N of the execution number counter stored in the RAM 43 are deleted. With such a configuration, it is made possible for the player to execute the special game under the desired condition irrespective of the specified number of times of special game.

With the slot machine 10 according to the present embodiment, an example is explained, in which control is taken so that in accordance with the increase in the number of specific symbols selected by the player rearranged in the display area 28, the payout amount is increased. As another embodiment, it may also be possible to take control so that the payout amount of credits is increased in accordance with the increase in the number of times of rearrangement of the specific symbol selected by the player in the display area 28. In this case, the appearance frequency of the symbol is counted as the number of times of game and therefore in the one-time special game, the count value will be “one” no matter how many symbols selected by the player are rearranged. Consequently, even if the ten times of special game are executed, the maximum of the count value is “ten”. In this case, even if the symbol has a small expectation value, the count value will be “one” if there is at least one symbol rearranged. Because of this, when the count value is the same, the smaller the expectation value, the more the payout amount is, and therefore, it is possible to further develop the player's interest in the game by selecting a symbol having a small expectation value to increase the probability of receiving a more payout amount of credits.

The embodiments of the slot machine according to the present embodiment are explained as above, however, they are only the concrete examples and not intended to limit the present invention, and the specific configuration of each unit etc. can be modified in design adequately. Further, the effects described in the embodiments of the present invention are only enumerated as most preferable effects that can be obtained from the present invention and the effects of the present invention are not limited to those described in the embodiments of the present invention.

For example, the controller 48 of the present invention can be constituted by a CPU that performs processing in accordance with programs, such as the controller 48 of the mother board 40 and the CPU 51 of the gaming board 50 in the slot machine in the present embodiment, but this is not limited and, for example, it may also be possible to constitute part of the controller 48 by a custom IC (Integrated Circuit) such as an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Processor). 

1. A slot machine comprising: a main display on which a plurality of symbols that have been arranged are rearranged in a unit game; a sub display on which an appearance frequency of a specific symbol and a payout amount of credits in accordance with the appearance frequency are displayed; and a controller operable to: (a) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, cause a predetermined number of times of special game as a unit game to be executed after the sub game, (b) vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, and (c) display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.
 2. The slot machine according to claim 1, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of specific symbols rearranged on the main display during the special game.
 3. The slot machine according to claim 1, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the special game.
 4. A slot machine comprising: a main display on which a plurality of symbols that have been arranged are rearranged in a unit game; a sub display on which an appearance frequency of a specific symbol and a payout amount of credits in accordance with the appearance frequency are displayed; and a controller operable to: (a) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, cause a predetermined number of times of special game as a unit game to be executed after the sub game, (b) vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, (c) increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout, and (d) display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.
 5. The slot machine according to claim 4, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of specific symbols rearranged on the main display during the special game.
 6. The slot machine according to claim 4, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the special game.
 7. A slot machine comprising: a main display on which a plurality of symbols that have been arranged are rearranged in a unit game; a sub display on which an appearance frequency of a specific symbol and a payout amount of credits in accordance with the appearance frequency are displayed; and a controller operable to: (a) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, cause a predetermined number of times of special game as a unit game to be executed after the sub game, (b) vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game, (c) increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout, and (d) update the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency each time each special game is over or the specific symbol is rearranged on the main display, and display them on the sub display.
 8. The slot machine according to claim 7, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of specific symbols rearranged on the main display during the special game.
 9. The slot machine according to claim 7, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the special game.
 10. A playing method executed in a slot machine, comprising the steps of: (a) causing a controller to rearrange a plurality of symbols that have been arranged on a main display in a unit game; (b) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, causing the controller to execute a predetermined number of times of special game as a unit game after the sub game, and to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game; and (c) causing the controller to display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.
 11. The playing method executed in a slot machine according to claim 10, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of specific symbols rearranged on the main display during the special game.
 12. The playing method executed in a slot machine according to claim 10, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the special game.
 13. A playing method executed in a slot machine, comprising the steps of: (a) causing a controller to rearrange a plurality of symbols that have been arranged on a main display in a unit game; (b) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, causing the controller to execute a predetermined number of times of special game as a unit game after the sub game, and to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game; (c) causing the controller to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and to reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout; and (d) causing the controller to display the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency on the sub display.
 14. The playing method executed in a slot machine according to claim 13, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of specific symbols rearranged on the main display during the special game.
 15. The playing method executed in a slot machine according to claim 13, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the special game.
 16. A playing method executed in a slot machine, comprising the steps of: (a) causing a controller to rearrange a plurality of symbols that have been arranged on a main display in a unit game; (b) when a sub game in which a specific symbol is selected from among the plurality of symbols by an external input was executed, causing the controller to execute a predetermined number of times of special game as a unit game after the sub game, and to vary the payout amount of credits in accordance with the appearance frequency of the specific symbol on the main display during the special game; (c) causing the controller to increase the payout amount of credits in accordance with the appearance frequency of the symbol more than that of the symbol having a larger expectation value of payout when the specific symbol is a symbol having a small expectation value of payout, and to reduce the payout amount of credits in accordance with the appearance frequency of the symbol less than that of the symbol having a smaller expectation value of payout when the specific symbol is a symbol having a large expectation value of payout; and (d) causing the controller to update the appearance frequency of the specific symbol on the main display and the payout amount of credits in accordance with the appearance frequency each time each special game is over or the specific symbol is rearranged on the main display, and to display them on the sub display.
 17. The playing method executed in a slot machine according to claim 16, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of specific symbols rearranged on the main display during the special game.
 18. The playing method executed in a slot machine according to claim 16, wherein the controller is operable to increase the payout amount of credits in accordance with the increase in the number of times the specific symbol is rearranged on the main display during the special game. 